Necrotic enteritis is an acute infection affecting galloanserans. Galloanserans are divided into the subgroups galliformes (landfowls) like chicken, turkey, grouse and pheasant, and anseriforms (waterfowls) like ducks, goose and swan. Necrotic enteritis has become an emerging problem especially among poultry and is characterized by severe necroses of intestinal mucosa. The clinical illness is usually very short and often the only signs are a sudden increase in mortality. However, birds with depression, ruffled feathers, and diarrhea may also be seen. The gross lesions are primarily found in the small intestine (jejunum), which may be ballooned, friable, and contain a foul-smelling, brown fluid.
The causative agent is the gram-positive, obligate, anaerobic bacteria Clostridium perfringens. There are two primary C. perfringens types, A and C, associated with necrotic enteritis in galloanserans. Toxins produced by the bacteria cause damage to the small intestine, but also liver lesions, and mortality.
C. perfringens is a nearly ubiquitous bacteria readily found in soil, dust, feces, feed, and used poultry litter. It is also a normal inhabitant of the intestines of healthy galloanserans.
Development of necrotic enteritis depends on the presence of predisposing factors, such as mucosal damage caused by coccidial pathogens and feed containing high protein levels.
Because C. perfringens is nearly ubiquitous, it is important to prevent coccidiosis, as well as changes in the intestinal microflora that would promote its growth. This has earlier been accomplished by routinely adding antibiotics to the feed. However, since the ban of growth promoting antibiotics in the European Union in 2006, necrotic enteritis has become an emerging disease among, for instance, poultry. There is a great need for alternative methods to counteract this disease or malfunction.
An alternative to counteracting harmful bacteria like C. perfringens through antibiotics is to try to balance or normalize the gut flora. The gut flora consists of a complex of microorganism species that live in the digestive tract. In this context gut is synonymous with intestinal and flora with microbiota and microflora. The microorganisms perform a host of useful functions, such as fermenting unused energy substrates, training the immune system, preventing growth of harmful, pathogenic bacteria, regulating the development of the gut, producing vitamins for the host and producing hormones to direct the host to store fats. However, in certain conditions, some species are thought to be capable of causing diseases or malfunction by producing infection or increasing cancer risk for the host.
The present invention discloses the use of a glycerol ester composition for preventing and/or alleviating necrotic enteritis in the gastric tract of galloanserans, like chicken and turkey. The use of said composition for modulating the gut flora of galloanserans is also disclosed. Use of the composition according to the invention balances or normalizes the gut flora of galloanserans in such a way that the growth of pathogenic species is inhibited and diseases like necrotic enteritis are prevented. One mechanism behind this effect is presently believed to be that the growth of helpful bacteria is favored and that this prevents the growth of pathogenic species by competing for nutrition and attachment sites to the epithelium of the colon.
The positive effects of butyric acid on gut health in poultry and other animals have been known for a long time. Different distribution forms of butyric acid have also been explored, among them distributing butyric acid in the form of glycerol esters. In recent years, a lot of interest has been directed to the use of glyceryl monobutyrate as a feed-additive to promote animal gut health.
Use of a glycerol ester composition, comprising mainly glyceryl tributyrate, has now surprisingly been found to be a more efficient way of preventing necrotic enteritis in galloanserans, such as broiler chicken, compared to giving the animal butyric acid in the form of glyceryl monobutyrate.